1. Field of the Invention
The present invention relates to a road shape determining device for determining the shape of a road ahead of the position of a vehicle on the basis of road data, and a vehicle control system for controlling the vehicle on the basis of the road shape determined by the road shape determining device.
2. Description of the Prior Art
A road shape determining device and a vehicle control system are known from Japanese Patent Application Laid-open No. 5-141979, in which the radius of curvature of a curve of the road is presumed by calculating the radius of an arc passing through three nodes, and an appropriate vehicle curve speed of the vehicle is calculated on the basis of the radius of curvature of the curve compared with a presumed vehicle curve speed of the vehicle calculated on the basis of the current vehicle speed. If the presumed vehicle curve speed of the vehicle is equal to or lower than the appropriate vehicle curve speed of the vehicle, it is determined that the vehicle can pass through the curve.
When the road is repaired after generating road data, or when there is a mistake in generating the road data, the actual road shape may not match with the road data. For example, in the case of FIG. 8, there is the following problem: The radius of curvature of the curve determined from the mistaken road data, is smaller than the radius of curvature of the curve of the actual road. For this reason, when a warning operation or an automatic braking operation is carried out so that the vehicle can pass through the curve having the smaller radius of curvature, an unnecessary warning or automatic braking operation is carried out to provide a sense of incompatibility to a driver.